When To Do Internships During Nuclear Engineering Education

Hello,
I will be beginning the Nuclear Engineering program at Oregon State University in the next couple of years and I have a question about internships. Most of the classes in the program are offered only one term per year so it seams I will be stuck with just doing summer internships or taking a year off ( this is already shaping up to be a 6 year degree). Will doing summer internships give me enough experience to make me competitive in grad school or entering the work force with just a BS? I was hoping to get some experience at one of the national labs Like Los Alamos or INL but I don't know how valuable this would be. I would love to hear from other people who have been in this situation.